Method of manufacturing magnetic storage elements

ABSTRACT

A process for the manufacture of a magnetic storage element useful in data processing apparatus. Said element is made by stacking a plurality of plates, made of a non-magnetic, and electrically insulating material, each of which has openings therein so that the openings of the stacked plates together form a recess for receiving a magnetic core. Some of the stacked plates have electrical conductors formed thereon by a printing method. The magnetic core is formed in situ in the stacked plates by solidifying a fluid mixture containing a magnetic material and a resinous binder within the recess.

United States Patent Hardung-Hardung 51 Apr. 18, 1972 54] METHOD OF MANUFACTURING 3,138,785 6/1964 Chapman et a1 ..340/174 MAGNETIC ST R E ELEMENTS 3,154,840 11/1964 Shahbender Inventor: Heimo Hardung-Hardung, Frankfurt am Main, Germany Vickers-Zimmer Aktiengeselschait Planung and Ben von lndustrieanlagen July 31, 1969 Assignee:

Filed:

Appl. No.:

Field of Search ..29/604; 340/174 MA, 174 M; 264/272, 273

References Cited UNITED STATES PATENTS -ooocnw Munk Primary Examiner-John F. Campbell Assistant Examiner-Carl E. Hall Attorney-Molinare, Allegretti, Newitt and Witcoff [57] ABSTRACT A process for the manufacture of a magnetic storage element useful in data processing apparatus. Said element is made by stacking a plurality of plates, made of a non-magnetic, and electrically insulating material, each of which has openings therein so that the openings of the stacked plates together form a recess for receiving a magnetic core. Some of the stacked plates have electrical conductors formed thereon by a printing method. The magnetic core is formed in situ in the stacked plates by solidifying a fluid mixture containing a magnetic material and a resinous binder within the recess.

2 Claims, Drawing Figures PATENTEBAPR 18 I972 3, 656,230

I sum 1 OF 2 FIG. 1(1 F|G. 1b

PATENTEDAPR 18 I972 SHEET 2 OF 2 FIG. 2

FIG. 3

IN VEN TOR.

METHOD OF MANUFACTURING MAGNETIC STORAGE ELEMENTS BACKGROUND OF THE INVENTION This invention relates to a process for the production of a magnetic information storage element for data processing apparatus, consisting of a carrier body made of a nonmagnetic, electrically insulating material and provided with a hollow space in the form of a magnetic core and at least one electric conductor which penetrates the magnetic core and which is produced by a printing process.

The essential constructional parts of a magnetic storage element are the magnetic core and at least one electric conductor. It is in the nature of the matter that the conductor must penetrate the magnetic core. The production of such a system is, in the case of individual storage elements, relatively uncomplicated. However, in the combining of individual storage elements into so-called matrices, rising difficulties are encountered. Hitherto, matrices with a large number of magnetic cores were assembled by hand; namely, the windings in the form of electric conductors were threaded through the cores, whereupon these were secured in the readied matrix. Such a type of assembling has become more and more time consuming and uneconomical, since arrangements are demanded with higher and higher capacity and an increasing number of cores. Simultaneously, there is a prevailing tendency to use cores of smaller and smaller dimensions which further makes the assembling task more difficult. The problem is further complicated by the fact that in general each core has at least three windings coupled inductively with the core, namely, a line or row winding, a column winding and a reading winding.

In order to minimize the problem of threading and securing individual electric conductor elements, attempts have already been made to produce the electric conductor according to the principle of the printed circuits. By this term it is meant the various methods comparable with the printing process, such as, for example, photographic processes, etching processes, metal spraying processes and printing processes in the classical sense or a combination of these, insofar as in these processes there results an electric current path on a generally required underlayer. Thus, for example, through Germany Pat. No. 1,040,140 it is a known practice to produce a matrix consisting of a plurality of ferromagnetic cores by embedding finished magnetic cores in depressions of an assembly plate and fixing them there by a casing composition, and subsequently carrying out the wiring on both sides of the assembly plate on past the cores and through one or more holes pro vided in its middle, for example, with a printing process.

Such a process proceeds from the insight that a threading of core and conductor without interruption of one of these structural parts cannot be avoided. The known process, however, is complicated and expensive, since in the first place there has to be produced an assembly place with sack-like depressions for the magnetic cores, which is done by use of a photosensitive plate, exposure and etching. Since the plane of the individual cores and the plane of the assembly plate are identical, the electrical conductors, in consequence of the necessity of penetrating the magnetic cores, have to be applied on both sides of the assembly plate and connected by electrical conductivity with one another through the cores. The difficulty lies above all in bringing the printed circuits on both sides into connection with one another. The electrical connection of the two circuit sides has to be brought about through a special operation. Such a production process, because of the twice-repeated exposure and etching processes, is extremely expensive and complicated.

German Pat. No. 1,025,651 discloses a polydimensional magnetic core storer, in which the carrying body or the assembly plate for the magnetic cores consists of several layers of a nonmagnetic material or insulating material. The individuallayers have perforations with equal division, but differing dimensions, the middle layer serving for the reception of the finished magnetic cores lying in a plane with it. The

plates are cemented together and the electrical windings are made in such a way that a flexible conductor is woven through the holes of the individual magnetic cores. The process is also extremely complicated.

Finally, through German Pat. No. 1,035,8l0, it is also a known practice to form in situ the individual ferrites in the place of their use, i.e., at the crossing points of the electrical conductors of a matrix, by applying; drops of a paste which consists of magnetic powder and binders. The drops, together with the matrix are subsequently heated, as is normally done for the production of sintered ferrites. Hereby, to be sure, there are avoided the threading of cores, the interweaving of electrical conductors and the complicated production of a circuit printed on both sides, but this process results in several other considerable drawbacks: Since the ferrite layer surrounding the electrical conductors generally does not suffice for the electrical insulation of the conductors among one another, the electrical conductors have to be insulated against one another at the crossing points before the application of the ferrite-forming composition in an additional operation, by layers of insulating material. Further, since a carrying plate or assembly plate for the electric conductor elements is not present, these have to be fixed in position in some manner or other until the hardening of the ferrite-forming drops. Furthennore, the process of the drop formation and of flowing around the crossing points of the electrical conductors results in considerable, if not, indeed, inadmissible tolerances in the characteristic data of the finished ferrite beads. Finally, the sintering at temperatures considerably above 1,000 C. prohibits the use of organic insulating substances, which are now indispensable for such matrices.

Underlying the present invention, therefore, is the problem of avoiding the drawbacks of the known production processes for storage elements and matrices as well as the disadvantages of the products themselves, and to create a process for the simple, rational production of storage elements and matrices, making use of printed circuits, in which no additional insulating processes are required, and in which the chracteristic data of the magnetic cores lie within the prescribed tolerances.

SUMMARY OF THE INVENTION The solution of the problem posed is achieved according to the invention by the means that the hollow space of the carrying body is filled with a fluid mixture of a magnetic powder and a solidifying'binder, in which the mixture first surrounds the electric conductor or conductors and subsequently hardens. In the object of the invention, accordingly, the carrying body serves as casting mold for the fluid composition forming the magnetic core. Consequently, through the preferably mechanical production of the hollow space inside the carrying body there can be maintained the closest tolerances for the forming magnetic cores. Further, it is possible to provide the carrying body with a printed circuit in the final state before the introduction of the fluid composition, since the fluid composition is capable of flowing around the electrical conductors and that part of the carrying body which serves in the zone of the hollow space for the support of the electrical conductor and forming a jointless core.

According to the invention, it is further proposed that the carrier body be composed of several pierced plates, at least one of the plates on at least one side is provided, by a printing process, with an electrical conductor. The openings on these plates possess such a form, size, position and number that after the placing one upon another of a corresponding number and type of plates in the carrying body there is formed an annular hollow space laying perpendicular to its plane, which space is subsequently filled with the fluid magnetic powder-binder mixture, whereupon this is caused to harden. The multilayer construction of the carrier body permits a very great breadth of variation in the.type of execution of the storage elements. The use of different number or combination of plates printed on one or two sides with continuous conductor elements permits the use of the storage element for various purposes, thus avoiding the necessity of a large number of special carrier bodies in stock for the purpose. As a rule, only two types of plates are needed, and, namely, one plate cross section for the upper cover plate or lower one, with a single perforation in the form of the projection of the magnetic core on a plane perpendicular to the plane of the magnetic core, and a second plate cross section with two perforations in an arrangement which corresponds to a central section through the finished magnetic core.

It can also be advantageous, however, to use plates of differing thickness, in order to limit the thickness of the carrying body. Thus, for example, the plates serving exclusively for the insulation of the electric conductors among one another or with respect to the magnetic core can be in the form of sheets or films.

BRIEF DESCRIPTION OF THE DRAWINGS AND DESCRIPTION OF THE PREFERRED EMBODIMENT In general, storage elements of the type described are not used singly, but are jointed into a matrix with a large number of magnetic cores. Here it is merely necessary to use plates for the construction of the carrying body which are provided with a large number of openings for a corresponding number of magnetic cores. The openings can be produced, for example, all in a single operation by a punch tool with a large number of stamp dies.

The process of the invention is especially well suited to the assembly-line type of production method, e.g., by the use of endless belts. The plates may be first appropriately printed with electrical conductors, continuously perforated and, by means of an adhesive composition, continuously united with one another, whereupon they are filled with the fluid magnetic core composition and subsequently cut up into strips with the desired dimensions.

For the purpose of the exact adjustment of the required characteristic data of the magnetic cores it may be under some circumstances necessary to obtain exactly fixed dimensions in the hardened magnetic cores. One dimension of the cores is dependent on the thickness of the carrying body, since the magnetic core extends over the entire thickness of the plate. The calibration, accordingly, can be accomplished in an extremely simple manner by a material-removing operation, for example, by grinding.

The invention will now be described in detail by examples, with the aid of FIGS. 1 to 3:

FIG. 1a to 1e show plan views of the individual plates of the carrying body, in part with printed conductor parts;

FIG. 1f shows the plates according to FIGS. 1a to 1e, which are stacked or placed one upon another in the sequence of the alphabet in figures;

FIG. 2 shows a section through the storage element of FIG. 1 f along the line A-A; and

FIG. 3 shows a section through a storage core matrix, in which the section plane lies in the plane of the reading wire.

In FIG. 1a, there is designated by the numeral 1 a plate such as is used as the upper and lower cover plate for a storage element. The plate 1 has a square form as well as a rectangular recess 2, whose surface configuration corresponds to the projection of the storage core on a plane perpendicular to the plane of the storage core, and whose longitudinal axis coincides with a diagonal of the square. In FIG. lb there is designated with the numeral 3 a plate which is arranged between the upper and lower cover plate according to FIG. 1a. It contains two recesses 4 and 5 of such a spatial-position and such dimensions as to correspond to the cross section through the center of gravity of the magnetic core. The axis of symmetry through the two recesses likewise runs in the diagonal of the square plate 3. The thickly drawn outer edges of the two recesses coincide in the placing of the plates one upon another with the contours of the rectangular recess 2 in FIG. la. The plate 3 serves exclusively for the insulation or spacing of the next-following plate. FIG. 10 shows a plate 6 which has the same outline as the plate according to FIG. lb, but with the difference that besides the recesses 4 and 5 there is present a printed-on electric conductor 7, which runs in the plate center and parallel to two edges of the square plate 6. Consequently, there lies between the axis of symmetry through the two recesses 4 and 5 and the printed-on conductor 7 an angle of 45. FIG. 1d shows a plate 8 of the same outline as FIG. lb, but in which there is printed electric conductor 9 which runs in the direction of the diagonal which stands at a right angle to the axis of symmetry through the two recesses 4 and 5. FIG. le shows a plate 10 of congruent outline, in which there is printed an electric conductor 11, which lies in plate center and parallel to two edges of the square plate, but, in comparison to the conductor 7 according to FIG. 10, offset by The plates are assembled according to the following sequence, the plates being identified by the above figure numbers and the upper plate being designated first: FIG. la, FIG. 1b, FIG. 1c, FIG. 1d, FIG.le and FIG. 1a. It is unnecessary to arrange under plate 12 a plate according to lb, since in the plate according to FIG. 1e only the upperside is printed with a conductor. Consequently, this plate itself serves as a closing insulator downward. The individual plates can now be cemented together or be held in a frame until the completion of the storage of the storage element. FIG. 1f shows a plane view of the plate stack which forms the carrying body, in which the electric conductors 7, 9 and 11, not visible from above, are represented by broken lines. The conductor 7 presents the so-called column winding, the conductor 9 the socalled reading winding, and the conductor 11 the row winding. All the conductors have a common crossing point 12, at which they are insulated and separated from one another by the plate thickness in each case and lie spatially one over another.

From FIG. 2 it is evident that the joining of the recesses 2, 4 and 5 leads to an annular hollow space 13, in the form of a closed rectangular ring, which is penetrated by the electrical conductors 7, 9 and 11. The hollow space 13 is filled with a flowable mixture of a magnetic powder and a binder, which is preferably solidifiable at room temperature. Suitable for this, for example, is a mixture of carbonyl iron powder, whose average particle size does not appreciably exceed 5 [L in diameter, and an unsaturated polyester resin. Such a mixture can be advantageously produced in a mixing ratio of resin to carbonyl iron powder of 1:6 (parts by weight). Larger amounts of resin constituents may be used. The limit of fluidity lies at about a weight ratio of 1:7. A mixture of 50 g of an unsaturated polyester resin (for example Polyleit D 4230 of ReicholdChemie, Hamburg) and 337.5 g of carbonyl iron powder, combined with 0.65 g of a 40 percent methyl-ethylketone peroxide and three drops of a 6 percent cobaltthaphthenate solution solidifies at room temperature with only slight heat toning of 30 to 40 C after about 30 minutes, and is completely hardened after about 2 hours. In the redox system methyl-ethyl-ketone peroxide/cobalt-naphthenate, the firstmentioned substance acts as catalyst and the second-mentioned substance acts as accelerator.

Mixtures successfully usable for the purpose of the invention can also be prepared with phenol casting resins, in which case a filling of these resins is possible up to a resin-iron weight ratio of 1:5 and can lie, preferably, between about 1:3 and 1:4. For example, a mixture of phenol resin (for example, Plyophen 62-061 of Reichold-Chemie, Hamburg) and carbonyl iron powder in the weight ratio of 1:5 hardens completely at temperatures between 80 and within 3 to 5 hours.

As magnetic powders there can be used, besides the carbonyl iron mentioned, powders from ferromagnetic alloys, oxides and oxide mixtures, and ferrites, for example, nickel or cadmium ferrites, manganese-cadmium ferrites, manganese-zinc ferrites. Suitable binders for the execution of the process of the invention are liquid or liquefiable plastics which can be filled sufficiently with a magnetic powder and then be solidified. Thus, for example, generally liquid condensation products or aromatic oxy compounds, such as phenols and cresols in conjunction with aldehydes, preferably formaldehyde, come into consideration. Other suitable binders are epoxide resins. Further, there can be used liquid condensation products of amines, for example, of aniline, or of urea, thiourea with aldehydes. The therrnoplasts, such as polystyrene, polyamides as well as acryl compounds, may also be used. The magnetic powder after thoroughly grinding is intimately mixed with the binder and then, preferably immediately, put into the hollow spaces in the carrying body.

The plane of the magnetic core lies, in consequence of the construction of the carrying body of several layers or plates of the type described, perpendicular to the plane of the carrying body. Consequently, the magnetic core is penetrated by the electrical conductors printed on the individual plates in planes which likewise lie perpendicular to the magnetic core. It is unnecessary, accordingly, to crop or offset the printed conductors in any manner. It is under some circumstances even superfluous to cement the individual layers of the carrying body together before the casting with the magnetic powder-binder mixture, since this mixture itself acts as a binding member in consequence of its adhesive properties and is in annular form enclosing the plate cross pieces between the openings 4 and 5.

FIG. 3 shows a cross section through a storage core matrix which has arisen through combining of several storage elements according to FIGS. 1 and 2. The carrying body is likewise composed of several layers or plates, of which, however, only one, 14, is visible. The carrying body contains sixteen magnetic cores 15, whose planes likewise lie perpendicular to the plane of the carrying body and, further, are aligned at an angle of 45 to the outer edges of the carrying body. The numeral 16 designates the column windings, and numeral 17 the row windings, each of which penetrates four magnetic cores in a straight line, but in different planes. In another plane or on another plate there is the printed reading winding 18, going through all the magnetic cores in a meander pattern. Column winding, row winding and reading winding form in each case a common crossing point in the interior space of each magnetic core. The design of the connecting points of the individual windings does not form a part of the invention and is, not, therefore, explained in detail. However, such design is known to those skilled in this art. Similarly, the functioning of magnetic core storers is also so well known that it is unnecessary to go into this in detail.

The invention has been described in detail with reference to particular and preferred embodiments thereof, but it will be understood that variations and modifications can be made within the spirit and scope of the invention as described hereinabove and as defined in the appended claims.

lclaim:

1. A process for the manufacture of a magnetic storage element for use in data processing apparatus which comprises:

a. forming a support by stacking a plurality of plates, the uppermost of said plates having a rectangular recess defined along the upper surface thereof, the lowermost of said plates having a rectangular recess defined along the lower surface thereof, said plates also having hollow recesses perpendicular to the surfaces thereof such that after said plates are stacked, the recesses of the plates form an annular, hollow, endless casting mold for receiving and retaining a magnetic core, said plates being made of a non-magnetic electrically insulating material;

b. printing an electrical conductor on at least a predetermined one of said plates within said support, at least a portion of the conductor being surrounded by said endless mold;

c. filling the annular hollow casting mold of said support with a fluid mixture containing a magnetic material and a resinous binder comprising an unsaturated polyester resin and carbonyl iron powders in a weight ratio about 1:6 and a catalytic amount of methyl-ethyl-ketone peroxide/cobalt-napthenate;

d. solidifying said fluid mixture at room temperature to form said magnetic core in situ' and e. trimming the solidified fluid mixture to a predetermined size.

2. A process for the manufacture of a magnetic storage element for use in data processing apparatus which comprises:

a. forming a support by stacking a plurality of plates, the uppermost of said plates having a rectangular recess defined along the upper surface thereof, the lowermost of said plates having a rectangular recess defined along the lower surface thereof, said plates also having hollow recesses perpendicular to the surfaces thereof such that after said plates are stacked, the recesses of the plates form an annular, hollow, endless casting mold for receiving and retaining a magnetic core, said plates being made of a non-magnetic electrically insulating material;

b. printing an electrical conductor on at least a predetermined one of said plates within said support, at least a portion of the conductor being surrounded by said endless mold;

c. filling the annular hollow casting mold of said support with a fluid mixture containing a magnetic material and a resinuous binder comprising a phenol casting resin and carbonyl iron powder in a weight ratio of between about 1:3 to 1:5;

d. solidifying said fluid mixture at a temperature between about and C; and

e. trimming the solidified fluid mixture to a predetermined size. 

2. A process for the manufacture of a magnetic storage element for use in data processing apparatus which comprises: a. forming a support by stacking a plurality of plates, the uppermost of said plates having a rectangular recess defined along the upper surface thereof, the lowermost of said plates having a rectangular recess defined along the lower surface thereof, said plates also having hollow recesses perpendicular to the surfaces thereof such that after said plates are stacked, the recesses of the plates form an annular, hollow, endless casting mold for receiving and retaining a magnetic core, said plates being made of a non-magnetic electrically insulating material; b. printing an electrical conductor on at least a predetermined one of said plates within said support, at least a portion of the conductor being surrounded by said endless mold; c. filling the annular hollow casting mold of said support with a fluid mixture containing a magnetic material and a resinuous binder comprising a phenol casting resin and carbonyl iron powder in a weight ratio of between about 1:3 to 1:5; d. solidifying said fluid mixture at a temperature between about 80* and 100* C; and e. trimming the solidified fluid mIxture to a predetermined size. 